They were made in Italy in the 1960/70s and rarely have any clues to designers. Sometimes a sticker can be found still in place, but this is believed to be more likely an importers mark, rather than manufacturer?
The pressed ones sometimes have 'Made in Italy' impressed on the bottoms, and always a (more sensibly a plastic bung, to make the stopper fit securely into the neck. The blown bottles never have this addition, and as they are hand blown, wobble and are pretty precarious.
They are a lovely thing to collect, as even now, I am still finding designs I have not seen before, and love the look of them all together. American factory Blenko made similar pieces too.
Note: This item has since sold